The present invention relates generally to auxiliary engine systems, and more particularly to such a system with two electrical actuators arranged in series on an electrical circuit.
Many electromechanical devices, including some fuel injectors, utilize two or more separate electrical actuators. This design offers numerous advantages over systems utilizing a single electrical actuator. Multiple actuator injection schemes enhance the potential control over valve actuation, allowing injection timing and duration, and fuel pressurization to be precisely controlled. In many cases, however, the additional hardware and circuitry necessary for a second actuator make its use cost-prohibitive. Moreover, system robustness and long term reliability may be compromised.
U.S. Pat. No. 6,113,014 to Coldren et al. discloses one method of incorporating a second electrical actuator into a fuel injector by wiring the solenoids in series. The use of a plurality of diodes in the circuit allows the solenoids to be selectively actuated, while avoiding the financial and functional problems associated with additional wiring and hardware. The Coldren design represents one successful way of addressing the problem, however, there is always room for improvement.
The present invention is directed to one or more of the problems associated with the prior art.
In one aspect, an engine is provided which comprises an engine housing defining at least one cylinder. At least one engine auxiliary system is attached to the engine housing and has a different portion associated with each of the at least one cylinder. Each different portion includes a first electrical actuator operably coupled to a first valve, and a second electrical actuator operably coupled to a second valve. An electrical circuit is associated with each of the at least one cylinder. In addition, the first electrical actuator and the second electrical actuator are arranged in series on the electrical circuit and are actuatable at a low current level and a high current level, respectively.
In another aspect, a fuel injection system is provided which comprises at least one body component, a first electrical actuator that is operably coupled to a fuel pressurizer, and a second electrical actuator that is operably coupled to a direct control needle valve. The first electrical actuator and the second electrical actuator are arranged in series on an electrical circuit and are actuatable at a low current level and a high current level, respectively. The first electrical actuator, the fuel pressurizer, the second electrical actuator, and the direct control needle valve are attached to the at least one body component.
In still another aspect, a method of controlling a portion of at least one engine auxiliary system associated with each engine cylinder is provided. The method includes the step of arranging a first electrical actuator and a second electrical actuator in series on an electrical circuit associated with each engine cylinder. The method also includes the step of actuating the first electrical actuator without actuating the second electrical actuator at least in part by establishing a relatively low current level in the electrical circuit. The method also includes the step of actuating the second electrical actuator at least in part by establishing a relatively high current level in the electrical circuit.